Research Progress on the Preparation of Biomass-Based Carbon for Energy Storage via Molten Salt Synthesis

To address issues such as environmental pollution and the greenhouse effect, it has become crucial to develop high-performance, low-cost, and environmentally friendly energy storage devices. As a sustainable, low-cost, and environmentally friendly natural renewable resource, biomass, along with biomass-based carbon derived from it, has significant application advantages in the field of energy storage in the future. Although biomass are widely available and cost-effective, transforming them into high-performance biomass-based carbon requires a series of complex processing steps, such as pretreatment, carbonization, and activation. These steps can increase production costs to some extent and may also lead to environmental pollution. In recent years, the molten salt synthesis has garnered significant attention due to its advantages of simple preparation processes, adjustable product structures, and minimal environmental pollution. This review mainly discusses the influencing factors of biomass-based carbon on the electrochemical performance, such as pore structure, specific surface area, and heteroatom doping. It also describes the roles of three types of molten salt compositions (metal carbonates, metal chlorides, and mixed salt systems) in the preparation process of biomass-based carbon. Finally, we look forward to the future research directions of the molten salt synthesis for preparing biomass-based carbon.